Agent Smith wrote:

Supposedly it's a boundary that wraps around to the other "side" of
the universe, with a reflection operation that may or may not exist.
It seems a wonderful opportunity to rewrite the old, 50's, sci-fi
movie, "Journey to the Far Side of the Sun," where a test pilot
travels to a mirror Earth, and everybody thinks that he aborted the
mission and came back, until he notices that everything is reversed.
Only the ending needs to be discarded.

That, and the mirror earth. Depart Earth, circumnavigate the universe,
and return to the your point of origin, and unless the universe is a
lot smaller than the likely minimum size, you'll find an
unrecognizable stellar neighborhood.

Mostly red dwarves, not much gas
or dust, nothing resembling the Sun. Search around enough and maybe
you'll find a cold dead ball of rock 7000km in radius, about 15-20
billion years old, with its frozen seas and continents in an
unfamiliar configuration, adrift in interstellar space. That's if it
wasn't evaporated from the galaxy by close encounters and the
civilization you left didn't get around to blowing it up or
cannibalizing it to build a Dyson sphere sometime after your
departure.

Actually, there probably wouldn't be any frozen seas. The water would
have boiled off during the red giant phase of the sun's life. Then
again, cometary impacts could have delivered more.

If the universe is small enough, and you go at nearly light speed, you
might find the planet still orbiting a white dwarf, not yet stripped
off it by some random encounter. Earlier still and heck, the planetary
nebula might still be there. You're sure to miss the red giant stage
though, unless the universe is less than about five billion light
years in circumference along the path you took and you went at just a
hair below lightspeed the whole way around.

Given the gas and dust that, at those speeds, would hit with extreme
force, such that a pebble would hit you like a megaton nuke, you would
probably have to set up a receiver in Earth orbit, travel to e.g.
Betelgeuse at a lower speed, build a transmitter that magnetically
hovers over one pole of the star, have yourself digitized and
downloaded into the transmitter, and then wait for the star to go
kablooey in a few million years or less. There should be powerful
gamma ray jets out the poles during the supernova according to some
models. The transmitter will be vaporized, but if built right it can
impose a modulation on those gamma rays as it goes. Then you zip
around at exactly light speed and arrive as red-shifted but detectable
radio waves at the receiver many billions of years later, if the
universe curves in on itself in the direction the gamma ray jet went.
Footprint should be galaxy-wide so wherever Earth ended up, if it
didn't get launched out of the galaxy by something's gravity, it
should be in the reception footprint. The receiver observes a high-Z
supernova in deep space, decodes a modulation, and reconstitutes you
in orbit of your cold, dead homeworld. A rather pointless stunt for
which only posthuman professionals need apply. Constructing a receiver
that will survive for billions of years in Earth orbit, including a
few billion years of every-90-minute 200-degree temperature swings
back and forth about room temperature, a few million years of roasting
during the sun's red giant phase, and then a few billion of freezing,
all without deorbiting even once, and still work after all of that is
left as an exercise for the reader.

Risks include:
* Not getting to Betelgeuse in time. It might go bang in 300,000 years
or in just 300. If it goes bang in 300, you'll still be only halfway
there or so. If it goes bang tomorrow and those polar jets are aimed
just wrong, your civilization might go up in smoke before you even get
to leave Earth.
* The transmitter might fail, especially if your detailed
supercomputer models of the evolution of the Betelgeuse supernova
prove to be wrong. * The universe might be too big, or cosmic
acceleration too strong, and space around your path proves to expand
faster than light can cross it. * Something might absorb the signal,
such as a large dust cloud, once it's redshifted enough.
* You might miss the Milky Way coming around the loop due to the
accumulated deflections of your path due to galaxies and dark matter
along the way. Being just a signal, you can't steer to correct your
course. * Someone might intercept you. You might wake up to find
yourself a "guest" of the Klingon Empire or something. Or being run in
thousands of death cubes by who knows what.
* The Earth might have been evaporated from the Milky Way.
* They *think* the swelling red giant Sun will shed enough mass for
the Earth to spiral outward and stay out of reach, but they may have
miscalculated and the Sun swells enough to swallow the Earth after
all. * The receiver might fail, or get cannibalized by some later
Earth civilization. Even if it becomes a holy shrine for humans and
none will ever dare touch it, a later civilization might not have the
same reverence; they eventually opened and took stuff from King Tut's
tomb, after all. And of course there's no guarantee that a later
civilization will actually be human at all. It might be AIs, or
extraterrestrial colonists, or some intelligent descendant of the
parakeet, or of the Salmonella bacterium that gave you the runs after
those bad tacos that time for that matter -- five billion years is
provably long enough for a bacterium's descendants to evolve into
intelligent tool-users with the ability to reach Earth orbit, because
it's already happened once. Biggest risks -- receiver simply fails to
last much longer than the Pyramids, or it gets fried by EMP during
WWIII after Emperor George Bush IV and Sultan Bin Laden Junior get
into a pissing match over a few spaceships intentionally crashed into
Moonbase domes or something equally silly and pointless.
* Planet's been disassembled long ago for some purpose or another.
* Those maniacs! They blew it up!
* After everything else works, the signal might be too weak or garbled
after all. You never wake up, or find you've been reconstructed as a
hybrid of a three-cushion sofa and a mountain hyena with two heads one
of which is permanently wedged up its *****. And your spacesuit
therefore won't fit.
* All hyped up at witnessing the cold cinder that used to be Earth,
you instead wake up to find ... Earth. Intact, with a thriving
civilization, if an incomprehensible one. They stabilized the star,
stabilized the planet, stuck nanotech into everything, and suchlike,
or perhaps the Matrix has you. Perhaps, halfway back to Earth you ran
into the expanding wave of machines converting everything into
nanoprocessors to run posthuman civilization on, and got downloaded
into same.

A journey that's definitely not for the faint of heart.

Dear Agent Smith:

On Feb 4, 4:06=A0pm, Agent Smith <agent-sm...@two-blocks-on-your-





left.com> wrote:

dlzc<dl...@cox.net> wrote in news:10053289-afc9-442b-948e-
a5910b3c7...@s8g2000prg.googlegroups.com:

On Feb 4, 1:15=A0pm, uri <dann...@bezeqint.net> wrote:

I believe the universe doesn't have a boundary.

You are in good company. =A0Current physics believe that there is no
boundary, just as the surface of a balloon has no boundary... on the
surface of the balloon.

It is infinite in scope.

This has issues. =A0It is true that you can send away from any point a=

c, and never have that light come back to the same point. =A0But there=
is no evidence that the Universe is infinite. =A0On the contrary, the
past displays a progressively hotter, denser youth, equally young and
hot in every direction... something an infinite Universe can only
handle if we are in a "special place".

Not at all. =A0Our universe might be a bubble that inflated at a decided=

unspecial location into a universe that already existed, pushing pre-
existing space out of the way.

What is it about "special place" that you don't understand? =A0"In the
bubble" *is* a special place. =A0"In the bubble" and "no other bubbles
have intruded" is yet another special place. =A0In an infinite Universe,
the probability that we are "in the bubble" is near zero.
Additionally, we are so close to "center of the bubble", that we
cannot see out of it to "spaces" that have different physics than we
have right here. =A0It is normal matter to the limit of our vision.

David A. Smith- Hide quoted text -

- Show quoted text -

Dear Agent Smith:

On Feb 4, 4:06 pm, Agent Smith <agent-sm...@two-blocks-on-your-
left.com> wrote:

dlzc<dl...@cox.net> wrote in news:10053289-afc9-442b-948e-
a5910b3c7...@s8g2000prg.googlegroups.com:

On Feb 4, 1:15 pm, uri <dann...@bezeqint.net> wrote:

I believe the universe doesn't have a boundary.

You are in good company.  Current physics believe that there is no
boundary, just as the surface of a balloon has no boundary... on
the surface of the balloon.

It is infinite in scope.

This has issues.  It is true that you can send away from any point
at c, and never have that light come back to the same point.  But
there is no evidence that the Universe is infinite.  On the
contrary, the past displays a progressively hotter, denser youth,
equally young and hot in every direction... something an infinite
Universe can only handle if we are in a "special place".

Not at all.  Our universe might be a bubble that inflated at a
decidedly

unspecial location into a universe that already existed, pushing pre-
existing space out of the way.

What is it about "special place" that you don't understand? "In the
bubble" *is* a special place. "In the bubble" and "no other bubbles
have intruded" is yet another special place. In an infinite Universe,
the probability that we are "in the bubble" is near zero.
Additionally, we are so close to "center of the bubble", that we
cannot see out of it to "spaces" that have different physics than we
have right here. It is normal matter to the limit of our vision.